Device for igniting explosive charges



April 29, 1969 P. MADLENER ET AL 3,440,962

DEVICE FOR IGNITING EXPLOSIVE CHARGES Filed May a, 1967 Sheet of 2 as Q April 29, 1969 P. MADLENER ETAL 3,440,962

DEVICE FOR IGNITING EXPLOSIVE CHARGES Filed May 5, 1967 Sheet 2 of 2 6 LT 36 Z United States Patent 3,440,962 DEVICE FOR IGNITING EXPLOSIVE CHARGES Paul Madlener, Karlsruhe-Durlach, and Otto Pecksen, Herrenalb, near Karlsruhe, Germany, assignors to Industrie-Werke Karlsruhe Aktiengesellschaft, Karlsruhe, Germany, a corporation of Germany Filed May 5, 1967, Ser. No. 636,392 Claims priority, application Germany, May 12, 1966,

Int. Cl. F42c 13/08 US. Cl. 10270.2 6 Claims ABSTRACT OF THE DISCLOSURE The invention relates to a device for igniting explosive charges by the use of an electrodynamic current generator.

In conventional current generators based on the dynamo principle, a magnetic field produced by a winding or by a permanent magnet has rotatably arranged therein an ignition coil upon which a plurality of windings is arranged. To effect an ignition it is necessary that first a spring be tensioned and secured against running off. Only upon release of the spring lock will the spring run off quickly, causing the coil to rotate and intersect with the lines of magnetic force so that an ignition current pulse is produced. This type of current generator has the disadvantage that its mechanics are rather involved. There is first required a spring with winding and locking means and, further, bearings or a shaft for the coil rotating in a magnet are necessary. Also, the windings for the ignition coil must be manufactured individually. Furthermore, if due to an inaccurate tensioning of the spring it runs off irregularly, the duration of the rotational motion of the ignition coil may vary, and this may result in ignition performances varying from case to case.

These disadvantages are overcome by the present invention the object of which is to produce an electrodynamic current generator which commands a powerful ignition capacity with the least possible mechanical complexity and with a small housing structure.

In accordance with the invention, for the purpose of testing the ignition cable and igniting the explosive charge, an ignition coil cooperating with ball locks is forced by a compression spring in a straight line into a cup-shaped magnet, whereby for producing a voltage and an ignition current pulse, respectively, the windings of the ignition coil intersect a strong magnetic flux in an air gap. Contrary to the prior art devices the coil nOW performs a linear motion and this has the advantage that the parts heretofore required for a rotational motion, such as bearings and a shaft for the ignition coil, or the like, are no longer required. With the disposal of such parts one source of trouble has also been eliminated. Another advantage resides in the fact that the ignition coil can be put to use for two purposes, namely for testing the ignition cable and for igniting the explosive charge.

According to the invention, a strong pretensioning is imparted to the compression spring so as to ensure that the ignition unit is thrust into the cup-shaped magnet always with the same speed and power when testing the ignition cable and inducing the ignition of the explosive charge. In this way the current generator will generate a constantly even voltage of a constant potential. Due to the compression spring, which has to be pretensioned after each phase of motion of the ignition coil, it is made certain that the voltage and the ignition capacity are maintained at an even constant value.

The device is characterized by an ignition unit in the form of a coil mounted upon a coil body in the housing of the current generator and which in unison with that body is sli-dably mounted in linear relationship upon a guide cylinder which has arranged in its interior ball locks adapted to be retensioned after an ignition has taken place. In this arrangement the guide cylinder has a twofold purpose, namely first to direct and guide the ignition coil mounted on the coil body in its forward motion, and second to accommodate the ball locks which hold the ignition coil in its starting position. A further advantage is that the ball locks are so constructed that they can be tensioned again after the ignition has been effected, which is not possible in conventional current generators.

Another feature of the invention is that the guide cylinder is provided with apertures through which the ball locks extend outwardly. The ball locks include balls which are movable at right angles with respect to the ignition coil and are received by an annular groove in a supporting ring and are disposed in sleeves carried by the guide cylinder. The diameter of the balls is larger than the interior diameter of the slot in the guide cylinder receiving the sleeves. In the interior of the guide cylinder are arranged locking levers which are pivotally mounted about axes and are engaged by a spring. The locking levers and the balls in the interior of the guide cylinder are in cooperation with each other in that the locking levers urge the balls against the wall of the guide cylinder so that they project a small distance through the openings in the wall of the guide cylinder and are received by an annular groove in the supporting ring. By a pivotal movement about their axes, the locking levers move toward each other, whereby the balls follow this movement and by their displacement release the ignition coil.

The locking levers are further engaged by the conical surface of a release button axially 'displaceable in a closure cap. When the release button is pushed, its conical surface acts upon the rounded ends of the locking levers and causes the latter to be pivotally moved about their axes,

A compression spring is arranged around the outer circumference of the guide cylinder and said spring in turn is surrounded by the ignition coil body. This compression spring which has been pretensioned in its starting position, after the withdrawal of the ball locks, causes the ignition coil arranged on the coil body to be propelled into the cup-shaped magnet. On its way the coil traverses an air gap between the cup-shaped magnet and the perimeter of the pole plate through which extends a magnetic flux.

The invention further provides a moving coil indicator arranged in the casing of the current generator and constructed as an indicating instrument having a rotatable roller with fields of different colors. With this modification the current generator is capable of being used not only for the igniting the explosive charge but also for testing the ignition circuit or cable before effecting the ignition. This has the advantage that the two operations can be performed by one single device, whereas a second device which was heretofore required for the ignition cable test can be dispensed with.

In the following the invention will be described in fur- 3 ther detail with reference to the accompanying drawings in which:

FIG. 1 is a partly sectional view of a current generator;

FIG. 2 illustrates in an elevation view a portion of the generator when viewed in the direction of the arrow A in FIG. 1;

FIG. 3 is a diagram for the test of the ignition cable, and FIG. 4 is a diagram for the ignition by the current generator.

In a housing 1 is installed a magnet system which is composed of a cup-shaped magnet 2, a cylindrical magnet core 3 and a pole plate 4. The magnet core 3 is made of a high quality magnetic material. To the pole plate 4 is attached by a threaded connection the release device for an ignition coil 6 secured to a tubular coil body 5. The coil body is movably arranged on a guide cylinder 9 and surrounds a supporting ring 7 and a compression spring 8. The compression spring 8 engages in its pretensioned condition with one end a surface 10 of the guide cylinder 9 and with its other end it engages the supporting ring 7 and the coil body 5 and thereby retains the latter in a locked position. The supporting ring 7 is provided in its inner circumferential wall with an annular groove 11 and with a surface 12 inclined toward the compression spring 8. In the interior of the guide cylinder 9 are deposited in a slot 13 the ball locks which have the form of balls 14a and 14b movable at right angles with respect to the ignition coil and arranged in sleeves 15a and 15b. The diameter of the balls 14a and 14b is larger than the clear width of the slot 13 receiving the sleeves 15a and 15b. The guide cylinder 9 is further provided with openings 16a and 16b through which the balls project a short distance in order to enter the annular groove 11 in the ring 7. In the slot 13 of the guide cylinder 9 are arranged locking levers 18a and 18b movable about transverse axes 17a and 17 b, and the levers at the level of the supporting ring 7 are engaged by the balls 14a and 14b and the inner ends of the sleeves 15a and 15b. A spring 19 causes the locking levers 18a and 18b to move apart so that they push the bals 14a and 14b into the annular groove 11. The free ends of the locking levers 18a and 18b which are positioned opposite the axes 17a and 17b are rounded and are engaged by the inner conical surface 20 of an axially displaceable release button 21 installed in a closure cap 22.

In that portion of the housing 1 which is opposite the closure cap 22, the retensioning device is arranged. The latter is also used as a safety element for the current generator. The cup-shaped magnet 2 is provided in its bottom Wall with apertures extending parallel to the axis of the magnet and through which project return movement pins 23a and 23b which in the tensioned state of the current generator engage the right-hand annular end face 24 of the ignition coil body 5. The pins 23a and 23b are fixedly attached to a pressure member 25 having a center cylindrical cavity 25a in which is arranged an ejector spring 26 which engages with one end the bottom face of the magnet 2 and with its other end the bottom of the cavity 25a. On a reduced cylindrical end portion of the pressure member 25, there is rotatably mounted by means of an annular spring 27 a resetting button 28 having an inwardly projecting nose 29 directed toward the ejector spring 26. The nose 29 is guided in the housing 1 by a radial groove 30 having an inclination of about 20 and is further guided in a groove 31 extending in axial direction of the pressure member 25.

In the housing 1 of the current generator is further arranged an indicating instrument in the form of a rotary coil 32 provided with a drum having a large area, as indicator for testing the closed ignition circuit. The rotary coil 32, in a manner well known, is surrounded by a stationary permanent magnet. The drum 33 is rotatable (FIG. 2) with the rotary coil 32 and is arranged behind a transparent cover 34. It is divided into diagonal areas of different colors, e.g. red and white. There are also provided two connector sockets 35 for the connection of the ignition cable, which is not illustrated, and for a shortcircuit key 36 whose butt-on 38 is covered by a rubber diaphragm 37 and must be depressed in order to trigger the ignition.

The operation of the electrodynamic current generator according to the invention is as follows:

(1) Testing of the ignition cable with the electrodynamic current generator For igniting an explosive charge one end of the ignition cable is connected to the explosive charge and the other end is plugged into the current generator at 35. First of all, however, a testing of the ignition cable for passage of current should take place and for this purpose the safety element of the current generator has to be released. This is accomplished by rotating the resetting button 28 to the left and simultaneously pressing it against the housing 1 so that its nose 29 slips out of the radial groove 30. Upon release of the resetting button 28 the latter is pushed outwardly by the ejector spring 26 which was tensioned up to this moment, and the button 28 with the nose 29 thereon slides along the vertical groove 31. At the same time, the pins 23a and 23b disengage the coil body 5 and with that the release of the current generator is completed therewith.

Upon depressing now the release button 21 the two locking levers 18a and 18b, which engage the inner conical surface 20 of the button 21, pivot about their axes 17a and 17b and converge, whereby the spring 19' is compressed and tensioned still more. This movement of the locking levers 18a and 18b has the result that the balls 14a and 14b move radially inwardly and leave the annular groove 11 in the inner wall of the supporting ring 7. At that instantdue to the fact that the ball locks are no longer effective-the ignition coil 6 fixed to the coil body 5 is propelled by the force of the pressure spring -8 in a straight line into the cup-shaped magnet 2. During this movement the windings of the ignition coil 6 intersect the magnetic flux in the air gap 39 and this generates a voltage pulse which is employed for testing the closed ignition circuit. When this occurs, the drum 33 on the rotary coil 32, which in the inoperative or zero position of the current generator displays a white field behind the transparent window cover 34, rotates until a red field becomes visible in the window, indicating to the observer that the ignition cable is in good working order and that the ignition process may be initiated.

(2) Retensioning of the electrodynamic current generator In order to ignite the explosive charge, the current generator must be retensioned. For this purpose, the resetting button 28 is slowly pushed toward the housing 1 causing the two pins 23a and 23b of the pressure member 25 to engage and move the coil body 5 back into its initial position as shown in FIG. 1 and thereby the compression spring 8 is tensioned again. At the same time, the supporting ring 7 disposed in the coil body 5 is moved toward the balls 14a and 14b and the inclined surface 12 of the ring 7 engages the ball surface until the balls due to this pressure are again radially moved into the annular groove 11. The balls 14a and 14b in turn permit the locking levers 18a and 18b to be pivoted about their axes 17a and 17b and to return to their initial horizontal position as shown in FIG. 1. Upon release of the resetting knob 28, it returns by the force of the ejector spring 26 to its former position.

(3) Ignition by means of the electrodynamic current generator In order to trigger the ignition of an explosive charge, the button 38 of the short-circuit key 36 must be depressed. This has the result that the resistance of the rotary coil 32 is short-circuited. Since the current generator is provided with a safety element, the ignition can be set off solely when the release button 21 is actuated. As has been described in paragraph (1) Testing of the ignition cable the ignition coil 6 is now propelled into the cup-shaped magnet 2 generating an ignition current pulse which causes the charge to detonate.

In the following will be described with reference to FIG. 3 the circuit for the testing of the ignition cable. After the current generator has been connected to the ignition cable including the fuse Z, the cable is ready to be tested by depressing the release button 21 which causes the ignition coil 6 to be propelled into the cup-shaped magnet 2. The voltage induced in the coil generates a test current which flow-s over the coil of the moving coil indicator 32 and the connecting socket 35a on to the fuse Z and returns over the connecting socket 35b to the ignition coil 6. The voltage drop in the rotary coil 32 is so great that the electric power is not sufficient to ignite the fuse. The rotary coil 32 receives an impact from the electric pulse in such a manner that the drum 33 rotates and the diagonal red field becomes visible. The short-circuit key 36 is not actuated during this test.

The circuit for effecting an ignition with the current generator illustrated in FIG. 4 is as follows: For the purpose of initiating the ignition, the short-circuit key 36 and the release button 21 are depressed simultaneously, causing the ignition coil 6 to be thrown into the cupsha-ped magnet 2. The ignition current thus generated flows over the short-circuit key 36, the connecting socket 35a and the ignition cable to the fuse Z and back over the connecting socket 35b to the coil 6. Now the full capacity of the current generator takes effect on the fuse.

What we claim is:

1. An electrodynamic current generator for testing ignition lines and for igniting remotely positioned explosive charges, including within a housing a magnet system comprising a stationary cup-shaped magnet, a cylindrical magnet attached within said cup-shaped magnet to the bottom wall thereof and means forming an annular air gap (39) within said cup-shaped magnet and exending around said cylindrical magnet, a guide cylinder attached to said cylindrical magnet, a tubular coil body having an ignition coil mounted thereon and slidably mounted on said guide cylinder, a compression spring within said coil body and engaging with one of its ends an annular shoulder within said coil body, ball locking means on said guide cylinder for holding said coil body in an initial position in which said ignition coil is disposed outside of said annular gap, a first manually operable means (21) for releasing said locking means and causing said compression spring to propel said coil body with the ignition coil thereon axially into said annular gap for producing current impulses for selectively testing ignition lines and igniting explosive charges, and a second manually operable means (28) for returning said released coil body and ignition coil thereon to its initial locked position,

2. A device according to claim 1, including a supporting ring within said coil body and surrounding said guide cylinder, an annular groove in the inner circumference of said supporting ring for receiving the balls of said ball locking means in the initial position of said coil body, radially positioned sleeves for said balls in said guide cylinder for permitting said balls to move at right angles to the axis of said guide cylinder and particularly into said annular groove of said supporting ring, parallel locking levers disposed parallel to the axis of said guide cylinder and pivotally mounted with one of their ends in said guide cylinder, said levers operatively engaging said balls, and a compression spring between the other ends of said levers for urging said levers apart and causing said balls to be urged into said annular groove in said supporting ring, said first manually operable means engaging the free ends of said levers and being adapted to move said levers toward each other so as to release said balls from their engagement with said locking ring.

3. A device according to claim 2, in which said first manually operable means comprises a release button axially movable along the axis of said guide cylinder in said housing and having an inner conical surface which engages the free ends of said levers.

4. A device according to claim 1, including .a supporting ring within said coil body and surrounding said guide cylinder, an annular groove in the inner circumference of said supporting ring for receiving the balls of said ball locking means in the initial position of said coil body, radially positioned sleeves for said balls in said guide cylinder for permitting said balls to move at right angles to the axis of said guide cylinder and particularly into said annular groove of said supporting ring, parallel locking levers disposed parallel to the axis of said guide cylinder and pivotally mounted with one of their ends in said guide cylinder, said levers operatively engaging said balls, and a compression spring between the other ends of said levers for urging said levers apart and causing said balls to be urged into said annular groove in said supporting ring, said first manually operable means engaging the free ends of said levers and being adapted to move said levers toward each other so as to release said balls from their engagement With said locking ring, said compression spring within said coil body surround-ing said two levers and said guide cylinder which carries said two levers.

5. A device according to claim 2, in which said second manually operable means comprises an axially movable resetting button arranged in axial alignment with said cup-shaped magnet on said housing and adapted to axially displace return movement pins which are disposed parallel to the axis of said cup-shaped magnet and extend through apertures in the bottom of said cup-shaped magnet for engaging one end face of said tubular coil body for effecting a re-locking of said ball locking means after its release.

6, A device according to claim 1, including an indicating instrument mounted in said housing and having a rotary coil arranged in a circuit conducting the produced current impulses to the ignition lines of the explosive charge to be ignited, an indicating drum fixedly connected with said rotary coil, and a switch on said housing adapted to short-circuit said rotary coil so as to conduct the encurrent impulses to the ignition lines of the explosive charge to effect its detonation, said switch in its open position permitting an energization of said rotary coil for testing and indicating by the position of said drum whether said ignition lines will be operative when said switch is closed.

References Cited UNITED STATES PATENTS 1,858,969 5/1932 Riihlemann l0270.2 2,703,530 3/1955 McGee l0270.2 2,754,760 7/1956 Wynn 102-70.2 2,966,856 1/1961 Tatel l0270.2 3,035,520 5/1962 Koeppen l0270.2 3,119,335 1/1964 Wyser l0270.2

FOREIGN PATENTS 506,280 5/1920 Italy.

VERLIN R. PENDEGRASS, Primary Examiner. 

